A British researcher by the name of David Keyes wrote a book called "Catastrophe". The main idea is that in the 6th century AD a vary large volcano (Krakatoa) exploded with significant global climate consequences. He ties in many social/political/historical events into the story. Very facsinating reading.

The Steppe horse is a small horse, 12 to 14 hands high, 800 to 1000 pounds. It was slower than the European destriers used by knights which themselves were 14 to 16 hands tall and 1000 to 1200 pounds.

But they had several advantages. Steppe ponies were far more rugged capable of surviving outside in Mongolian weather which goes from -30 to 40C. They had more endurance. In a short space they were slower than the larger Europeans but over 100 miles the steppe pony could move faster for longer. They could eat grass. European war horses had to be fed fodder (oats, wheat etc.) a mongol horse could survive on grazing alone. This gave the Mongol armies a much smaller logistical footprint.

Mongolians like small light motorcycles that go a long distance and won't run out of fuel or break down out on open grassland. Something big and ostentatious like a Harley is asking for trouble.

Suppose the tests had shown drought conditions over these years. Would this have been sufficient basis for the researchers to hypothesise a "push" factor in Genghis Khan's conquests, i.e. that poor conditions at home led to pressure on grazing and other resources, which led him to seek pastures new? An example perhaps of the dangers of ex-post rationalisations, or hindsight in interpreting history..

Good point! While it's possible that global warming created conditions that assisted Genghis Khan in his conquests, it seems that there's no way to be certain that it had any effect on how those events played out. Depending on the way a researcher wants to interpret the data, there is probably enough evidence to support lots of different theories. I think that the historic data the article is offering is interesting, but it doesn't seem like a conclusion can really be made about what any of it means.

This is the first record that allows for a fuller investigation of the climatic conditions for the rise and fall of this empire. Now the arc of the empire can be viewed in a temperature and precipitation based context.

You are making a good point, but you are missing the important point that is supply of available energy. The biggest mistake of humans is fail to understand energy cycle and thermodynamics. Plants create food using solar energy. So, plant biomass (grass or trees) is ultimate supply of energy. Even energy in grains or fruits is solar energy too. That supply is further converted into meat or milk, or any other animal product.

It is possible that conditions would have been poor and those conditions led him to conquer first place. But, to conquer further places, you need energy. So, first victory would have been complemented by technology, weapons, leadership, but after than supply of energy is VERY important in keep things going.

To begin with, the population of the world was about 450 million in the 13th century when Genghis flourished. The current world population is over 7 billion. Genghis's world-view was limited to Asia and environs. The world-view today covers the globe: we are instantly aware of the effects of climate change elsewhere.

And wetter is not necessarily better: a slightly changed weather pattern in 2010 saw record heat waves, forest fires and droughts in Russia, while Pakistan was stricken by the worst floods in memory. Humankind cannot predict where the effects of increasing temperatures and changing weather patterns will occur, only that they will occur.

This is the greatest threat of global warming/climate change: unpredictability. Imagine a drought striking India in mid-summer, accompanied by a failed monsoon. Imagine that same climate shift causing epic rain and flooding in Bangladesh. Or heat and drought wiping out 90% of America's crops.

Humans have been very lucky over the past 12,000 years or so, benefiting from relatively stable, relatively predictable weather systems. The climate catastrophes of the past few decades are only a foretaste of what's to come as the planet continues heating up. The politicians yammer on, but remediation of the problem hasn't even begun on the scale of what needs to happen.

Famines due to crop failure were caused as much by too much rainfall as too little historically. That is, changes in seasonal rainfall patterns such as too much in too short a time beating down grain-laden crops. Its about climatic equability.

The effects of overall warming are not the same everywhere: in places that are prone to droughts they will get worse, and in rainy places it will rain more. Also, even though some lands will vanish, like low-lying islands and coastlines, vast territories will be rendered inhabitable, in Siberia and northern Canada, which will be like having available a second planet without having to go terraform Mars, which would take too long anyway. The problem is that this is only the foreseeable. Too many unexpected things can happen: pandemics, a supervolcano exploding in Yellowstone Park, a reversal of the planetary magnetic field, an asteroid or comet impact, a straightening of the terrestrial axis and the ensuing worldwide hyperquakes, a nuclear war, or an invasion of evil extraterrestrials. Who can place these matters in their proper order, according to their degree of probability? War would have to be at the top of the list, anyway.

It led to prosperity in one place, but do you have data for every place on earth? many places during that could be facing drought. People often cite Greenland or some cold places that prospered, but fail to account for what happened in Tropical countries.

Indeed, Genghis was lucky there wasn’t a nasty cold snap when he was drinking the muddy waters of Baljuna. Or imagine a suddenly frigid cold snap back when Adam and Eve were just starting to chat about the apple?